1. Field of the Invention
The present invention relates to a pump driven by a hard drive type brushless direct current (DC) spindle-motor, suitable for use with liquid cooling systems.
2. Description of the Related Art
Liquid cooling is well known in the art of cooling electronics. As air cooling heat sinks continue to be pushed to new performance levels, so has their cost, complexity, and weight. Liquid cooling systems provide advantages over air cooling in terms of heat removal rates, component reliability and package size.
Liquid cooling removes energy from heat generating components through sensible or latent heat gains of a cooling fluid. The cooling fluid is continuously pressurized by a pump and may be delivered to a thermal management block. The cooling fluid may also be dispensed within a globally cooled enclosure. After the cooling fluid is heated by an electronic component to be cooled, the surplus energy of the fluid is removed by a heat exchanger, or condenser. The cooled fluid exits the heat exchanger and is delivered back to the pump, thus forming a closed loop system.
There are many different liquid cooling systems. Although each type of liquid cooling system may have a unique thermal management block, the closed loop cooling systems are likely to share the common need of pressurizing a supply of liquid coolant. For example: U.S. Pat. No. 6,234,240 discloses a single phase closed loop cooling system; a microchannel liquid cooling system is described by U.S. Pat. No. 4,450,472; an exemplary liquid cooling system is described by U.S. Pat. No. 5,220,804 for a two-phase spray cooling system utilizing a thermal management block; and a globally liquid cooled enclosure is described by U.S. Pat. No. 6,139,361. As described by the '804 patent, spray cooling is capable of absorbing high heat fluxes. Nozzles, or preferably atomizers, break up a supply of liquid coolant into numerous droplets that impinge the surface to be cooled. The size, velocity and resulting momentum of the droplets contributes to the ability of the thermal management unit to absorb heat. These characteristics, and thus the overall performance of the thermal management system are impacted by the performance of the pump. To achieve reliable system performance, it is important that the pump deliver accurate performance over a long life cycle. It is known that pumps driven by DC motors can be used with liquid cooling pumps. U.S. Pat. No. 6,447,270 describes a large scale DC brushless motor used for spray cooling. U.S. Pat. No. 6,193,760 describes a highly specialized DC brushless motor system wherein a rotor creates both the pumping and motor force. U.S. Pat. No. 5,731,954 describes a brushless motor mounted within a reservoir casing.
Desirable features of any liquid cooling system are low cost, high reliability and high performance. Optimization of the pump impacts all three features. Thus, there is a need for a pump that contains a motor with a proven history of high reliability. Thus, there is a need for a pump that contains a motor that can be produced for a low cost. Thus, there is a need for a pump that is compact in size. Furthermore, there is a need for a pump that is efficient in creating its output. Also furthermore, there is a need for a pump that is capable of producing significant pressures.